East Carbon City reviews sewer lagoon project

Residents of East Carbon and Sunnyside may soon be rid of the smell of sewage drifting across Utah Highway 123.

On Aug. 22, construction management for the rehabilitation of the sewer lagoons serving the two cities gave a status report at the East Carbon council meeting.

Warren Monroe, construction manager for the project, told city officials at the meeting that the lagoons are close to completion and should go into operation within the next few weeks.

One question brought up by city officials related to the size of the lagoons.

Originally constructed in the mid 1970s, the lagoon system was designed to handle a community with a population much greater than it is now.

In order to work effectively, sewer lagoons rely on a certain amount of water - at least three feet in depth - where bacteria and microorganisms work to break down sewage.

With a smaller population, East Carbon officials have questioned whether the city will be able to maintain the necessary level for the lagoons to operate effectively.

"The only concern is that this is going to come back to haunt us," said Councilmember Dave Maggio, noting that the city has seen problems after many recent improvements in the community.

After natural gas lines were installed in the 1990s, the city faced problems with streets and sidewalks.

ECDC, originally promoted as an economic lifesaver for the community after mines closed, has all but gone belly-up.

Maggio also pointed to East Carbon High as an example, where the swimming pool had been closed within months of the approval on a bond to upgrade the school. Then the entire high school closed last year.

However, Maggio also noted that other projects overseen by the project engineer, Jones and Demille Engineering, had been done properly and the city hadn't seen problems yet.

Monroe assured the council that the engineering firm would stand by its work and deal with problems relating to the revitalized lagoon system as they come up.

"We're not going to leave you hanging," said Monroe.

Each sewer lagoon needed extensive repairs prior to the project.

One of the main problems related to the clay lining, whichkeeps sewage from seeping into the ground, explained Monroe. If clay linings are too thin, water will seep through the lining and into the ground, lowering the depth of the lagoon.

As lagoon levels drop, breakdown of sewage slows. One side effect of the failure has been apparent to residents of East Carbon and Sunnyside, who have endured the smell of raw sewage in the communities in recent years.

Permeability tests performed prior to construction on cells two and three failed, said Monroe. Clay in the two cells was not tight enough.

Though the city has primarily used cell one, engineers used the test data from cells two and three to determine the overall scope of the project.

Prior to construction, engineers had not been able to perform tests on cell one, because it was in use and filled.

The other requirement facing engineers was to increase the depth of the lagoons.

When the lagoons were built, they had been designed with a depth of four feet.

Current requirements dictate that the depth be increased to six feet.

To start the project, construction crews upgraded the clay lining on cell three, which is the tertiary cell of the lagoon system.

The system was designed to use cell one first, with cells two and three as overflows to handle excess amounts of sewage from the cities.

While the clay lining in cell three was upgraded, it was not brought up to the same permeability rating as cells one and two.

The contents of cell one were then cycled into cell three for the duration of the construction project. Part of the reason that east county residents have experienced an unpleasant smell during the past year of construction is that cell three has served as a temporary lagoon and has not been brought up to the waster level where it would work properly.

In the past year, construction crews have repaired the lining in cells one and two.

Currently, crews are waiting on the valves which will connect the lagoons and allow overflow to flow into secondary and tertiary lagoons.

Once the valves are installed, cell one will again become the primary lagoon and the Utah Department of Environmental Quality will need to issue a permit for the system.

As part of the process, construction managers, city officials and state inspectors will have the opportunity to review the quality of work completed.

Monroe reported that cell one had an irregular bottom and that the clay lining was extremely thin in places. Those assessments were in line with what was expected after studying cells two and three, he said.

After revitalizing cells one and two, Monroe said that the lining now exceeds the requirements established by the Utah Department of Environmental Quality. Cell three, is still lower than the minimum for primary and secondary lagoons, but will work as a third lagoon if it is ever needed.

Because the lagoons cascade in elevation, the city cannot use cell two as its primary, because cell three fails to meet requirements as a secondary, nor can cell one be used because it is higher in elevation than cell two.

Although city officials have raised concerns regarding the lagoons, Monroe said the system should work as designed. Engineers used the most recent data available regarding flow rates to determine the approach to take. Based on the data available prior to construction, the size of the lagoons is appropriate.